durable-objects

Durable Objects provide per-entity storage, deterministic routing, and edge-local execution to build stateful coordination services on Cloudflare. They fit scenarios like chat rooms, multiplayer matches, and booking systems.

Use Durable Objects when coordination logic requires persistent state that stateless Workers lose. They provide one instance per entity, ensuring consistent behavior for real-time WebSocket-style handlers and scheduled per-entity work.

Manage Durable Object SQLite storage by defining migrations via your wrangler configuration file. This ensures your durable primary data schema is versioned and correctly applied during deployment.

Use blockConcurrencyWhile sparingly, applying it only for Durable Object initialization. For regular request handling, implement RPC methods instead of fetch handlers to manage entity interactions.

Test Durable Objects by configuring and running your suite using @cloudflare/vitest-pool-workers. This pool supports unit and integration testing patterns specifically designed for the Cloudflare Workers runtime.

Yes, you can schedule per-Durable Object background work using alarms. This allows individual entities like game matches or user sessions to execute delayed or recurring tasks deterministically at the edge.